/Engine/Source/Editor/MaterialEditor/Public/MaterialEditingLibrary.h
Duplicates the provided material expression adding it to the same material / material function, and copying parameters. Note: Does not duplicate transient properties (Ex: GraphNode).
static [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * DuplicateMaterialExpression ( [UMaterial](API\Runtime\Engine\Materials\UMaterial) * Material, [UMaterialFunction](API\Runtime\Engine\Materials\UMaterialFunction) * MaterialFunction, [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * Expression )